Serialise Instant as ISO 8601 string, Duration as number of milliseconds, and allow registering of custom TypeAdapterFactories

src/main/java/org/arl/fjage/remote/DurationTypeAdapter.java

@@ -0,0 +1,27 @@
+package org.arl.fjage.remote;
+
+import java.time.Duration;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.stream.JsonToken;
+
+public class DurationTypeAdapter extends TypeAdapter<Duration> {
+  @Override
+  public void write(JsonWriter out, Duration value) throws java.io.IOException {
+    if (value == null) {
+      out.nullValue();
+      return;
+    }
+    out.value(value.toMillis());
+  }
+  @Override
+  public Duration read(JsonReader in) throws java.io.IOException {
+    if (in.peek() == JsonToken.NULL) {
+      in.nextNull();
+      return null;
+    }
+    return Duration.ofMillis(in.nextLong());
+  }
+}

src/main/java/org/arl/fjage/remote/InstantTypeAdapter.java

@@ -0,0 +1,27 @@
+package org.arl.fjage.remote;
+
+import java.time.Instant;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.stream.JsonToken;
+
+public class InstantTypeAdapter extends TypeAdapter<Instant> {
+  @Override
+  public void write(JsonWriter out, Instant value) throws java.io.IOException {
+    if (value == null) {
+      out.nullValue();
+      return;
+    }
+    out.value(value.toString());
+  }
+  @Override
+  public Instant read(JsonReader in) throws java.io.IOException {
+    if (in.peek() == JsonToken.NULL) {
+      in.nextNull();
+      return null;
+    }
+    return Instant.parse(in.nextString());
+  }
+}

src/main/java/org/arl/fjage/remote/JsonMessage.java

@@ -11,7 +11,12 @@
 package org.arl.fjage.remote;
 
 import java.util.Date;
+import java.time.Instant;
+import java.time.Duration;
 import com.google.gson.*;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.stream.JsonToken;
 import org.arl.fjage.AgentID;
 import org.arl.fjage.Message;
 import org.arl.fjage.param.Parameter;
@@ -42,6 +47,8 @@ public class JsonMessage {
     .registerTypeAdapter(Double.class, (JsonSerializer<Double>) (value, type, jsonSerializationContext) -> value.isNaN()?null:new JsonPrimitive(value))
     .registerTypeAdapter(Date.class, (JsonDeserializer<Date>) (json, typeOfT, context) -> new Date(json.getAsJsonPrimitive().getAsLong()))
     .registerTypeAdapter(Date.class, (JsonSerializer<Date>) (date, type, jsonSerializationContext) -> new JsonPrimitive(date.getTime()))
+    .registerTypeAdapter(Instant.class, new InstantTypeAdapter())
+    .registerTypeAdapter(Duration.class, new DurationTypeAdapter())
     .registerTypeHierarchyAdapter(AgentID.class, new AgentIDAdapter())
     .registerTypeHierarchyAdapter(Parameter.class, new EnumTypeAdapter())
     .registerTypeAdapterFactory(new MessageAdapterFactory())
@@ -59,6 +66,11 @@ public static void addTypeHierarchyAdapter(Class<?> cls, Object adapter) {
     gson = gsonBuilder.create();
   }
 
+  public static void addTypeAdapterFactory(TypeAdapterFactory factory) {
+    gsonBuilder.registerTypeAdapterFactory(factory);
+    gson = gsonBuilder.create();
+  }
+
   public static JsonMessage fromJson(String s) {
     return gson.fromJson(s, JsonMessage.class);
   }